ABSTRACTA simple and reliable way of phenotyping plant responses to dehydration was developed. Fully-developed leaves were detached and placed in a closed plastic box containing a salt solution to control the atmospheric water potential in the container. Three hours of dehydration (weight loss of the leaf) was optimal for measuring changes in stomatal response to dehydration. Application of the plant hormone abscisic acid (ABA) prior to leaf detachment decreased the amount of water loss, indicating that the assay was able to detect differences based on a stomatal response to dehydration. Five different Vitis genotypes (V. riparia, V. champinii, V. vinifera cv. Shiraz, V. vinifera cv. Grenache and V. vinifera cv. Cabernet Sauvignon) with known differences in drought tolerance were screened for their dehydration response and the results obtained corresponded to previous reports of stomatal responses in the vineyard. Significant differences in stomatal density along with differences in the amount and rate of water lost indicate differences in dehydration sensitivity among the genotypes screened. Differences in stomatal response to ABA were also detected. Shiraz had the lowest stomatal density and the highest ABA sensitivity among the genotypes screened, yet Shiraz lost the most amount of water, indicating that it was the least sensitive to dehydration. Despite having the highest stomatal density and intermediate stomatal sensitivity to ABA, V. riparia lost the smallest amount of water, indicating that it was the most sensitive to dehydration. The assay presented here represents a simple and reliable phenotyping method for plant responses to leaf dehydration.

fig6: Stomatal density measurements of five grapevine genotypes. Data are expressed as the mean±s.e.m. (n=3).

Mentions:
One possible explanation for the different rates of water loss was that the leaves from each genotype had differences in their stomatal density. If this were the case, Shiraz, which lost the most amount of water, would have the largest stomatal density of the five genotypes surveyed here and Riparia Gloire would have the lowest stomatal density. In fact, there were highly significant differences (p≤0.01) among the genotypes (Figure 6; Supplementary data for Fig. 5C). Shiraz had the lowest stomatal density and Riparia Gloire had one of the highest, the exact opposite of the prediction if stomatal density was a factor. These results indicated that during the dehydration assay, Shiraz failed to respond by closing its stomata and continued to lose water. Also, despite having the largest stomatal density, Riparia Gloire had the lowest rate of water loss per leaf mass and lost the smallest amount of water, which indicated a higher sensitivity to dehydration.

fig6: Stomatal density measurements of five grapevine genotypes. Data are expressed as the mean±s.e.m. (n=3).

Mentions:
One possible explanation for the different rates of water loss was that the leaves from each genotype had differences in their stomatal density. If this were the case, Shiraz, which lost the most amount of water, would have the largest stomatal density of the five genotypes surveyed here and Riparia Gloire would have the lowest stomatal density. In fact, there were highly significant differences (p≤0.01) among the genotypes (Figure 6; Supplementary data for Fig. 5C). Shiraz had the lowest stomatal density and Riparia Gloire had one of the highest, the exact opposite of the prediction if stomatal density was a factor. These results indicated that during the dehydration assay, Shiraz failed to respond by closing its stomata and continued to lose water. Also, despite having the largest stomatal density, Riparia Gloire had the lowest rate of water loss per leaf mass and lost the smallest amount of water, which indicated a higher sensitivity to dehydration.

ABSTRACTA simple and reliable way of phenotyping plant responses to dehydration was developed. Fully-developed leaves were detached and placed in a closed plastic box containing a salt solution to control the atmospheric water potential in the container. Three hours of dehydration (weight loss of the leaf) was optimal for measuring changes in stomatal response to dehydration. Application of the plant hormone abscisic acid (ABA) prior to leaf detachment decreased the amount of water loss, indicating that the assay was able to detect differences based on a stomatal response to dehydration. Five different Vitis genotypes (V. riparia, V. champinii, V. vinifera cv. Shiraz, V. vinifera cv. Grenache and V. vinifera cv. Cabernet Sauvignon) with known differences in drought tolerance were screened for their dehydration response and the results obtained corresponded to previous reports of stomatal responses in the vineyard. Significant differences in stomatal density along with differences in the amount and rate of water lost indicate differences in dehydration sensitivity among the genotypes screened. Differences in stomatal response to ABA were also detected. Shiraz had the lowest stomatal density and the highest ABA sensitivity among the genotypes screened, yet Shiraz lost the most amount of water, indicating that it was the least sensitive to dehydration. Despite having the highest stomatal density and intermediate stomatal sensitivity to ABA, V. riparia lost the smallest amount of water, indicating that it was the most sensitive to dehydration. The assay presented here represents a simple and reliable phenotyping method for plant responses to leaf dehydration.